Mobile communication systems developed to provide the subscribers with voice communication services on the move. With the rapid advance of technologies, the mobile communication systems have evolved to support high speed data communication services as well as the standard voice communication services. However, the limited resource and user requirements for higher speed services in the current mobile communication system spur the evolution to more advanced mobile communication systems. Long Term Evolution (LTE) is a next generation wireless communication technology standardized by the 3rd Generation Partnership Project (3GPP) to meet the requirements. LTE is a high speed packet-based communication technology supporting up to 100 Mbps downlink data rate.
FIG. 1 is a diagram illustrating a legacy wireless communication system.
As shown in FIG. 1, the wireless communication system includes a User Equipment (UE) 100, a Macro enhanced Node B (macro eNB) 102, a Mobility Management Entity (MME) 104, a Serving Gateway (SGW) 106, and a Packet Data Network Gateway (PGW).
The macro eNB 102 is the base station managing a macro cell. Here, the macro cell means a cell of a normal cellular system. The macro eNB 102 is the base station of managing and controlling the macro cell. However, the terms ‘macro cell’ and ‘macro eNB’ are used in the same meaning for the convenience purpose. Accordingly, the eNB 102 managing the macro cell is referred to as macro eNB 102.
The macro eNB 102 establishes a radio channel with the User Equipment (UE) 100 and controls radio resources. For example, the macro eNB 102 may broad cast system information generated with the control information specific to the macro cell. The macro eNB 102 may allocate radio resource for communicating data and control information with the UE 100. The system information includes information on the operation supported by the eNB, i.e. Public Land Mobile Network Identifier (PLMN ID), eNB Cell Global ID (ECGI), and Tracking Area ID (TAI). The macro eNB 102 collects channel measurement result information of the serving and neighbor cells from the UE 100 and analyzes the information to make a handover decision and command handover. For this purse, the macro eNB 102 is provided with a control protocol such as Radio Resource Control Protocol for managing radio resources.
The MME 104 manages the UE in idle mode and selects PGW 108 and SGW 106. The MME 104 is also responsible for roaming and authentication of the UE 100. The MME 104 also process bearer signal generated by the UE 100. Typically, the MME 104 and UE 100 exchange Non Access Stratum (NAS) messages.
The MME 104 may support multiple TAIs and establish connection with the eNBs supporting the individual TAI. The eNBs 102 supporting the same TAI has the connection to the same MME 104, and the eNBs 102 supporting different TAIs are likely to have the connection to different MMEs.
The SGW 106 serves as a mobility anchor for UE's handover between macro eNBs or between 3GPP networks.
The PGW 108 allocates Internet Protocol (IP) address of the UE 100, performs core network's packet data-related function, and serves as a mobility anchor for handover between non-3GPP radio networks. The PGW 180 also determines a bearer band to be provided to the subscriber and is responsible for packet data forwarding and routing functions.
Typically, the eNB 102 and the MME 104 connect through an S1-MME interface, the eNB 102 and the SGW 106 connect through S1-U interface, and the SGW 106 and PGW 108 connect through S5 interface. The Home Subscriber Server (HSS) 114 stores per-UE subscription information. When the UE 102 tries to connect to a network, the HSS 114 provides the MME 104 with the information on the UE 102 such that the MME 104 controls the UE 102.
In the case of attaching to the macro eNB 102, the UE connects to the data network through the data transmission path 100 established via the macro eNB 102, SGW 106, and POW 108. In a typical wireless communication network, the UE 100 establishes the macro eNB 102 and sends the MME 104 a NAS request message. At this time, the NAS message may be any of Attach Request, Tracking Area Update Request, and Service Request. The UE 100 may communicate with a Dynamic Host Configuration Protocol (DHCP) server, a Domain Name Server (DNS) server, a web server, a File Transfer Protocol (FTP) server, a streaming server. The UE 100 request the server 112 for contents and the server 120 responds to the UE 100.
FIG. 2 is a signal flow diagram illustrating a procedure of acquiring contents in a conventional wireless communication system. Particularly, FIG. 2 shows the interoperation between the terminal and servers in which the terminal 200 connects to the contents server to acquire contents.
Referring to FIG. 2, the terminal 200 sends the DNS server a DNS request message including Uniform Resource Locator (URL) of the server having the intended content at operation 208. The DNS server 204 sends the terminal 200 a DNS response message including the IP address of the content server 206 at operation 210. Accordingly, the terminal 200 may send the content server 206 a message.
The terminal 200 sends a Content Request message, at operation 212, to the IP address of the content server 206 which is provided by the DNS server 204. Then the content server 206 sends the terminal 200 a Content Response message including the requested content at operation 214. Here, the messages exchanged between the terminal 200, the DNS server 204, and the content server 206 at operations 208, 210, 212, and 214 are relayed via eNB/SGW/PGW.